1. Field of the Invention
This invention relates to diisothiazoles and more particularly to a tricyclic heterocyclic ring system, 1,4-dithiino[2,3-c; 6,5-c']diisothiazole and ring-substituted derivatives thereof.
2. Relation to the Prior Art
The applicant is not aware of any art which discloses the tricyclic isothiazole ring systems of this invention. U.S. Pat. No. 3,101,344 issued Aug. 20, 1963, to R. D. Vest discloses bicyclic p-dithiino[c]isothiazole-3,5,6-tricarbonitrile, thus, ##STR1## as a side product in the preparation of tetracyano-1,4-dithiin. Simmons et al., J. Am. Chem. Soc. 84, 4746 (1962), disclose the preparation of this tricarbonitrile by reaction of tetracyano-1,4-dithiin with sulfur, iodine and sodium iodide at 25.degree. C.